Although progress has been forthcoming concerning macroecological patterns across large spatial scales, relatively little attention has focused on their temporal dynamics. Investigation of the macroecological patterns of mammalian body size distributions suggests that modern patterns from North America have been strongly affected by the end-Pleistocene extinction event (Lyons et al. 2004, Smith et al., 2004). Moreover, mammalian body size distributions settled into a bimodal distribution early in mammalian evolution (~40 ma) and remained that way until the extinction of large mammals 10,000 ya (Lyons and Smith, submitted). Other macroecological patterns are consistent across time. For example, body size/range size patterns in mammals have not changed over the last 40,000 years despite considerable changes in climate and a size biased extinction event (Lyons and Smith, submitted).

I am also investigating the role of body size in structuring communities through time and across the globe. Examination of ~300 local assemblages over the last 40,000 years indicates that despite the considerable turnover in community composition, body size distributions have stayed relatively uniform. Such results imply that body size is an important factor in determining membership in communities. However, extension of this work to include ~300 Recent communities across the globe indicates a significant latitudinal gradient in the shape of local body size distributions. Tropical communities have higher kurtosis values and thus more peaked distributions than temperate ones (Lyons, in prep). Preliminary analyses indicate that the shape of these distributions is correlated with climatic variables. Moreover, the ecological traits of the organisms that make up these communities differ among communities with the same general habitat characteristics, climate and elevation.

Future work will focus of the role of ecological traits in structuring communities across space and time. In particular, I am interested in the interaction between ecological traits and body size distributions.

S. K. Lyons and P. J. Wagner. 2009. Using macroecological approach to the fossil record to help inform conservation biology. Pp. 141-166 In: Conservation Paleobiology: Using the Past to Manage for the Future. Paleontological Society Short Course Volume 15.

Phanerozoic body size trends in time and space: Macroevolution and macroecology NESCent Project Site

The identification and explanation of long-term evolutionary trends in higher taxa and biological communities is an important goal of biological research. Body size is the single most important ecological characteristic of metazoa and the variable most easily applied to analysis of evolutionary trends across distantly related taxa. The proposed working group will bring together paleobiologists studying body size evolution in deep time and across higher taxa with biologists studying the distribution of body sizes in living organisms from the community to global scale. The working group will initiate a community-wide database of body sizes through the Phanerozoic, an effort that requires standardized data on body size across higher taxa. The working group will also catalyze collaborations between paleobiologists and biologists to develop the theory necessary to investigate long-term dynamics in body-size evolution across diverse living and extinct metazoan lineages. The workshop will provide a venue for members to address the relationships between the pattern of body size evolution and the distribution of body sizes in extant organisms. How well can macroevolutionary patterns be inferred from macroecological ones? How well do those patterns reflect evolutionary mechanisms, whether driven or passive? Ultimately, the resulting database will become a broadly applicable and dynamic resource for macroevolutionary research, with real potential to help future workers shed light on the forces that have shaped the evolutionary trajectory of animal life on Earth.